Painting in a symmetrical pattern is not an easy endeavour, this is when photo shop comes into play.  Upon completing some of my paintings, I consider taking them into photo shop and fool around with textile ideas.  
Original, 12" x 9" Acrylic on canvas 
I then cut and flipped the image, and extended the bottom.  
I then felt the desire to pull it back to make a less complicated piece.  You can add in all directions to make a multitude of ideas to play with.
Enjoy the adventures of creating via your  computer after the paint has dried.
~ Callie
www.CallieArtl.com